LA TERAL VENTRICLES 



69" 



Keil is then obtained. Lastly, the student sliould make a series uftliin sagittal sections thiouirh 

 the island of Keil and the iVoMtal lube until the great transverse fissure and its relation to the 

 descending cornu of the lateral ventricle is seen (fig. 417). The sections will pass through the 

 lenticular and caudate nuclei ol'the corpus striatum and through the optic thalamus. 



The inferior or descending cornu pursues a more curved and complieated 

 course than the other two coruua. It is directed at first outwards and backwards, 

 and then l)ends somewhat sharply downwards; lastly, it sweeps forwards Avith an 

 inclination inwards, following the long axis of the tem})oro-sphenoidal lobe. In 

 transverse section it is seen to be somewhat triangular, jjresenting a floor, an inner 

 wall, and a curved roof which bounds the cavity above and externally. The floor 

 is formed by the eminentia collateralis. The following structures appear on the 

 inner Avail: — the hippocampus major, ending in the pes hii)pocampi; the corpus 

 fimbriatum; and the choroid plexus, the latter aj^parently passing through a fissure 

 (the great transverse fissure). The roof is formed from within outwards by the 

 taenia semicircularis, by the narrow posterior prolongation of the caudate nucleus 



Fig. 417. — A Dissectiox of the Descexdixg Cokxu of the Lateral Yextricle, 

 AVITH A Sagittal Section through the Basal Gaxglia. 



FORNIX 



CORPUS CALLOSVM 



Choroid plexus 



FORCEPS MA JO P. 

 aiPPOCAMPr- 

 MI.\ 

 T.EXIA SE.Uir/E< 

 LABIS Fl.VBI 



OPTIC THALAM 

 CORPrs (;emi:. 



ISTERSCM 

 EMISESTIA COLLA- 

 TERALIS 

 CRVS CEREBRI 

 FASCIA D EXT AT A 



OPTIC TRACT 



LEyilCrLAR XCCLECS CAUDATE XUCLEUS 



of the corpus striatum, and by the tapetum. At the extremity of the cornu tlie 

 roof is formed by the amygdaloid tubercle. The taenia semicircularis and caudate 

 nucleus may be traced to this tubercle. 



The eminentia collateralis is a smooth triangular elevation, Avhich commences 

 in the interA-al betAveen the hippocampus major and minor, and extends, narroAving 

 as it proceeds, nearly to the extremity of the descending cornu. It is the indenta- 

 tion of the ventricular Avail produced by the collateral fissure. 



The hippocampus major, or cornu Ammonis, is a curved Avhite body Avhich 

 ends in a blunt extremity (})cs hijjpocampi), on Avhich are small indentations, 

 giving it an obscure resemblance to the paAv of an animal. It corresponds tn the 

 dentate fissure. 



The corpus fimbriatum, taenia hippocampi, or fimbria, is a narrow strip of 

 Avhite matter Avith a somewhat Avavy appearance, Avhich is i>laced along the concave 

 side of the hippocampus major. It is formed by a portion of the fibres of the 

 fornix continued into the descending cornu, and presents apparently a free edge 

 toAvards the transverse fissure, but is in reality continued into the eiiithelium Avhich 



